Ultra-large bottom opening and closing type three-dimensional loading apparatus and test method

An ultra-large bottom opening and closing type three-dimensional loading apparatus, comprising:

• a horizontal reaction frame, a vertical reaction frame, a sample bearing lifting walking beam, four lifting cylinders, a reaction support pad beam, array type actuator groups, and a linear array dynamic actuator group, wherein the horizontal reaction frame adopts a ring scarf structure, and is mounted on four high-strength reinforced concrete support piers;
• a height of each high-strength reinforced concrete support pier is higher than that of an ultra-large physical model sample, and a bottom of the high-strength reinforced concrete support pier is the same in elevation as a ground floor;
• a vertical central axis of the vertical reaction frame coincides with that of the horizontal reaction frame, a lower end of the vertical reaction frame is locally located in a foundation pit, and the lower end of the vertical reaction frame is fixed to a bottom of the foundation pit through anchor bolts;
• the sample bearing lifting walking beam is mounted at a middle of the vertical reaction frame and located below a lower surface of the horizontal reaction frame;
• the sample bearing lifting walking beam is connected to four corners at a top of the vertical reaction frame through the four lifting cylinders;
• one array type actuator group is arranged on a lower surface of the top of the vertical reaction frame;
• four array type actuator groups are uniformly distributed on an inner side of the horizontal reaction frame along a circumference direction;
• a through type actuator is arranged in one of the four array type actuator groups, and a robot excavation entering and exiting channel is disposed in the horizontal reaction frame directly opposite to a through hole of the through type actuator;
• one linear array dynamic actuator group is arranged at an upper part of the sample bearing lifting walking beam;
• and an entering and exiting opening for the ultra-large physical model sample and an entering and exiting opening for the reaction support pad beam are respectively formed in a crotch part between the high-strength reinforced concrete support piers below the horizontal reaction frame.